1. To ride in the front passenger seat of a vehicle, next to the driver
   "I called 'shotgun' and got to ride shotgun on our road trip"
    
2. To assist and protect someone, especially while they are performing a task
   "As the new employee learned the ropes, his mentor rode shotgun to ensure everything went smoothly"

Derived forms: riding shotgun, ridden shotgun, rode shotgun, rides shotgun

Encyclopedia: Ride shotgun